Nordmende Transita 120 IR Instruction Manual page 60

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Data compression
By doing so, digital radio takes advantage of the properties of human hearing. The human ear
does not detect tones which are below a certain minimum loudness. Data which are under the
so-called audibility threshold can, therefore, be filtered out. This is possible because, in a digital
data stream, the relevant relative volume for other units is saved for every unit of information.
Moreover, in an audio signal, the quieter parts are superimposed by louder ones at a specific
limit value. All the sound information below the threshold of hearing in a piece of music can be
filtered out of the signal to be broadcast. This reduces the size of the datastream to be broadcast
without a perceptible difference in sound for the listener (MUSICAM procedure).
Audio stream
With digital radio, audio streams are continuous data streams which contain the MPEG 1
audio layer 2 frames and thereby represent acoustic information. This enables standard radio
channels to be broadcast and listened to on the receiver side. Digital radio uses the MUSICAM
format with two MPEG-compliant PADs for additional information. These are also known as PAD
data services. Digital radio provides you with not only radio in excellent sound quality but also
additional information. The information may be about the current programme (e.g. title and
artist) or something else (e.g. news, weather, traffic and tips). To do so, please refer to Section
Improving antenna reception in this instruction manual.
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